Analysis of epoxidized natural rubber. A comparative study of d.s.c., n.m.r., elemental analysis and direct titration methods

A comparative analysis of epoxidized natural rubber samples by ¹H and ¹³C n.m.r., titrimetric, elemental and d.s.c. techniques has been made. Whereas the titrimetric method is only applicable at low epoxy contents (< 15 mol%) both n.m.r. methods give reasonable precision over the compositional range of 20–75 mol%. Elemental analysis appears less reliable. D.s.c. analysis through measurement of T_g provides the highest precision of measurement but requires independent calibration by one or more of the primary methods. The epoxy content may also be related to the polymer density.     

Assessment of a redox alkaline/iron-chelate absorption process for the removal of dilute hydrogen sulfide in air emissions

The oxidative absorption of hydrogen sulfide (H₂S) into a solution of ferric chelate of trans-1,2- diaminocyclohexanetetraacetate (CDTA) was studied in a counter-current laboratory column randomly packed with 15 mm plastic Ralu rings. The present investigation takes concern about the Kraft pulping situation where dilute H₂S concentrations are omnipresent in large-volume gas effluents. A fractional two-level factorial approach was instigated to determine the significance of six operating variables, namely the solution's alkalinity (pH; 8.5-10.5), the liquid mass flow rate (L;1.73-), the solution's ionic strength (I_C;0.01-), the gas mass flow rate (G;0.19-), the inlet H₂S concentration (C_H2S,0;70-430 ppm) and the initial ferric CDTA concentration (C_Fe,0;100 -). Initially, a Plackett-Burman design matrix of seven duplicated experiments revealed that pH is the leading factor controlling the H₂S conversion rate while the ionic strength and ferric CDTA concentration effects remained negligible within the factorial domain. Surface response analysis based on 11 duplicated factorial experiments plus 10 central composite trials revealed that the H₂S conversion significantly increases with liquid flow rate but decreases with growing H₂S load up. Further examination about the influence of ferric CDTA on H₂S absorption rate was set up over a broader concentration range (C_Fe,0;0- at pH of 9.5 and 10.5. It showed good potential at as H₂S conversion increased by a significant 25% for both pH values in comparison to pure alkaline solutions containing no ferric CDTA.     

方法研究在X公司机加工车间的应用

为改善X公司机加工车间不合理的生产方式,通过现场观察和咨询,对其血液分析仪不规范的装配流程运用"5W1H"提问技术并结合"ECRS"原则进行分析、改善,制定出标准的装配流程;针对同步带齿轮的加工过程中时间利用不科学的问题,运用人机操作分析法进行分析,同时改进齿轮的设计,最终使得人机加工周程时间节约了25 s,齿轮的增值时间利用率由原来的43 %增加到59 %,这些活动为该公司进行的生产管理改善提供了依据.     

Electrochemical behavior of K3Fe（CN）6 in water-in-oil microemulsion

A water-in-oil (W/O) microemulsion composed of Triton X-100, n-hexanol, n-hexane and water solution with hydrochloric acid was prepared. K₃Fe(CN)₆ was added in as a water-soluble electroactive probe, and its electrochemical behavior was investigated by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). It is found that the H⁺ concentration of the water phase has a great effect on the conductivity of the W/O microemulsion, and hence influences the electrochemical behavior of K₃Fe(CN)₆. When the pH value of water phase is about 7, the electrical conductivity of the W/O microemulsion is only 1.2×10⁻⁶ S/cm, and K₃Fe(CN)₆ almost cannot react at the glassy carbon electrode. But when the H⁺ concentration is more than 3 mol/L, the W/O microemulsion has a good electrical conductivity and K₃Fe(CN)₆ shows good electrochemical performance in it. The results of CV and EIS studies indicate that the electrochemical behavior of Fe(CN)₆ ³⁻/Fe(CN)₆ ⁴⁻ in the W/O microemulsion is different from that in the aqueous solution. This may be due to the unique liquid structure of the W/O microemulsion and the unique mass transfer in the W/O microemulsion. Foundation item: Projects(20673036, J0830415) supported by the National Natural Science Foundation of China; Projects(05JT1026, 2007JT2013) supported by the Science Technology Project of Hunan Province, China     

W UMa型相接双星V523 Cas测光研究

对V523 Cas（W UMa型）相接双星系统进行了测光观测,并通过IRAF软件经行了测光处理,获得了其自转周期.双星系统的掩食过程中主极小和次主极小红化分别为0m.07和0m.06;主极大与相随的次主极大在V和B波段分别相差0m.018和0m.022,V523 Cas为非对称的短周期W UMa型相接双星.     

层状化合物Bi_2W_2O_9的制备及其酸交换性质研究

采用高温固相法合成了层状Bi2W2O9,随后通过酸化处理得到H2W2O7·nH2O。采用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、红外光谱(IR)对产物进行了表征。结果表明,采用高温固相法可获得层状结构的Bi2W2O9,层间距1.2 nm。经酸交换后的H2W2O7.nH2O仍保持层状结构,但层间距略变小。     

清香木姜子的化学成分Ⅱ

利用硅胶柱层析分离及与标准品对照等方法从清香木姜子枝叶中分离得到4个化合物,1H NMR、13C NMR等技术及理化性质鉴定为:黄堇碱(1)、二十二酸(2)、二十六酸(3)、三十酸(4)。以上化合物均系首次从该植物中分离得到。     

建筑卫生陶瓷行业竞争环境SWOT分析

文章通过大量的调查研究,概述了中国特别是广东省建筑卫生陶瓷企业的现状,采用SWOT分析方法,对该行业的企业所处的优势、劣势、面对的机遇和挑战进行了全面的研究分析,预测了建筑卫生陶瓷未来发展的总体趋势。     

Complex formation in a ternary system composed of lauroamphoglycinate, oleic acid, and water

The formation of a complex, composed of lauroamphoglycinate (LG), oleic acid (OA) and water, was investigated, and this system was applied to emulsification. The complex was formed in the water-rich area (more than 90% in this system) at a molar ratio of OA to LG from 1 to 3, where two-phase systems of water and the complex existed. The interaction between LG and OA, both in the aqueous solution and at the interface of liquid paraffin dissolving the OA and LG solution, was studied by pH measurements and interfacial tension measurements, respectively. The results implied that LG and OA were linked stoichiometrically, both in aqueous solution and at the interface, and formed complexes. X-ray diffraction patterns and the strong hydrophobicity showed that the equimolar complex composed of LG, OA, and water was a liquid crystal with a reversed hexagonal structure. The reversed hexagonal liquid crystal was capable of solubilizing a certain amount of liquid paraffin in its alkyl group parts while maintaining its hexagonal structure. These results suggest the possibility to prepare a W/O-type emulsion by using the liquid crystal formed by LG, OA, partial liquid paraffin, and water as the continuous phase. The authors could obtain a stable W/O emulsion without coalescence of the water droplets that contained a substantial amount of water (approximately 90%). Furthermore, various types of emulsions, O/W, W/O, W/O/W, could be prepared by changing the ratio of LG and OA.     

稠油W/O型乳状液表观粘度变化微观原因解析

研究表明在一定温度和剪切速率条件下,一定油品的稠油W/O型乳状液表观粘度随含水率的增加呈现先增加后降低的趋势.基于这种变化现象的微观原因,本文从相、分子取向和原油胶体结构模型氢键理论3个方面进行系统的阐述.同时根据以上3种解释理论,对于不同性质的稠油W/O型乳状液转相点不同的原因也进行探讨分析,验证了3种解释理论的正确性.一般密度大和粘度高的原油所含胶质和沥青质等天然的W/O型乳化剂较多,W/O型乳状液的转相点亦较高.由稠油乳状液表观粘度变化及相转化过程对稠油的开发进行思考,不同稠油油藏初始含水饱和度使稠油乳状液表观粘度变化及相转化过程不同,分析认为考虑相转换对进一步深入认识油藏水驱规律具有较大的研究意义.